I sprayned my shoulder about 1,5 years ago (had physiotherapy and and all that), after one f## year I could do only 20 before this strange pain and cracking would set in, now I'm at 25-30.
I always used to hate pushups, then I just started doing some for fun in the evenings and after about 3 weeks I was at 50. After 2 months I could do 50, take a 2 minute rest and do 50 again and I *loved* it, until I jacked up my shoulder...
I guess what I'm saying is: enjoy the pushups and do some for mee as well, I would love to be able to go at them full power again...
And also what I found out: a limiting factor for me were the belly muscles, not the arms. As the belly belly grew stronger, the number of pushups increased